Contactor assembly for testing electrical circuits

ABSTRACT

The invention provides a contactor assembly. The contactor assembly comprises an electrical contactor including a contactor substrate, a plurality of electrical terminals on the contactor substrate; an interposer including an electrically conductive interposer substrate having first and second sides, a plurality of first and second resilient interconnection elements extending respectively from the first and second sides of the interposer substrate, wherein the interposer is positioned in a predetermined position relative to the electrical contactor in which predetermined position each first resilient interconnection element makes electrical contact with an electrical terminal of the electrical contactor, the interposer substrate having been moved relatively towards the contactor substrate to resiliently deform the first resilient interconnection elements; and a retaining component having a first portion secured to the electrical contactor and a second portion in contact with the interposer to retain the interposer in the predetermined position relative to the electrical contactor.

FIELD OF THE INVENTION

This invention relates to test equipment. In particular, it relates totest equipment for testing electrical circuits including integratedcircuits.

BACKGROUND

When fabrication of electronic devices, such as computer processors andmemories, have been completed, the electronic devices are subjected toburn-in and electrical testing in order to identify and eliminatedefective devices before shipment. The term “burn-in” relates tooperation of an integrated circuit at a predetermined temperature ortemperature profile, typically an elevated temperature in an oven.Certain operating electrical bias levels and/or signals are supplied tothe electronic devices while they are at the elevated temperature. Theuse of the elevated temperature accelerates stress to which the devicesare subjected during burn-in, so that marginal devices that wouldotherwise fail shortly after being placed in service fail duringburn-in, and are therefore not shipped.

Test equipment for burn-in testing of electrical circuits generallycomprise a connection arrangement for electrically connecting anelectrical circuit to be tested such as an integrated circuit on a waferor test substrate, to a test probe circuit.

SUMMARY

In one embodiment, the invention provides a contactor assembly for usein testing electrical circuits. The contactor assembly comprises anelectrical contactor including a contactor substrate, and a plurality ofelectrical terminals; an interposer including an interposer substratehaving first and second sides, a plurality of first and second resilientinterconnection elements extending respectively from the first andsecond sides of the interposer substrate, wherein the interposer ispositioned in a predetermined position relative to the electricalcontactor in which predetermined position each first resilientinterconnection element makes electrical contact with an electricalterminal of the electrical contactor, the interposer substrate havingbeen moved relatively towards the contactor substrate to resilientlydeform the first resilient interconnection spring elements; and aretaining component having a first portion secured to the electricalcontactor and a second portion in contact with the interposer to retainthe interposer in the predetermined position relative to the electricalcontactor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described by way of example with reference to theaccompanying drawings wherein:

FIG. 1 is a block diagram of an interposer, an electrical contactor anda wafer comprising circuits to be tested;

FIG. 2 is a block diagram of a contactor assembly in accordance with oneembodiment of the invention;

FIG. 3 is a block diagram illustrating a stage in the formation of thecontactor assembly of FIG. 2;

FIG. 4 is a perspective view of a vacuum plate connected to a ring, inaccordance with one embodiment of the invention;

FIG. 5 is a top plan view of the vacuum plate and ring of FIG. 4;

FIG. 6 is a section on 6-6 in FIG. 5;

FIG. 7 is a block diagram illustrating how a ring and interposer seatedtherein may be aligned with a contactor, in accordance with oneembodiment of the invention;

FIG. 8 is a perspective view of an alignment machine in accordance withone embodiment of the invention;

FIG. 9 is an end view of the alignment machine shown in FIG. 8 of thedrawings with a microscope mounted thereon;

FIG. 10 is a perspective view of the alignment machine of FIG. 8 mountedon a probe plate;

FIG. 11 is an end view of FIG. 10; and

FIG. 12 is a block diagram of a test probe assembly in accordance withone embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 of the accompanying drawings illustrates an interposer 10 and anelectrical contactor 26 which together form a contactor assembly,according to an embodiment of the invention, used to test electricalcircuits, for example, on a wafer 32.

As will be seen from FIG. 1, the interposer 10 includes a substratehaving a first side 12 and a second side 14. The interposer 10 includesa number of electrical terminals 16 on the first side 12. The interposer10 also includes resilient interconnection elements in the form ofinterconnection spring elements 18. Each interconnection spring element18 extends from an electrical terminal 16 on the side 12 and terminatesin a free end. The purpose of each interconnection spring elements 16 isto make good electrical contact with corresponding electrical terminalson the electrical contactor 26. In other embodiments, the resilientinterconnection elements include pogo pins and compliant conductivebumps.

The interposer 10 also has an interconnection spring element 20 on eachelectrical terminal 16 on side 14. The interconnection spring elements20 are similar to the interconnection spring elements 18 except that theinterconnection spring elements 20 are for making electrical contactwith corresponding electrical terminals on the wafer 32.

The interposer also includes mechanical stops 22 on the sides 12 and 14to prevent overtravel of the interconnection spring elements 18 and toprevent the interposer from touching certain areas of the wafer 32.

The electrical contactor 26 includes a contactor substrate whichincludes a side 28. Electrical contactor 26 also includes electricalterminals 30 on the side 28.

The wafer 32 is shown to include a side 34 which has the electricalcircuits to be tested. The wafer 32 has electrical terminals 36 on theside 34 whereby electrical connection to the electrical circuits may bemade.

FIG. 2 of the drawings shows a contactor assembly 40 in accordance withone embodiment of the invention. The assembly 40 includes an interposer10 and a retaining component in the form of a ring 42. The interposer 10is secured or held in a predetermined z position relative to theelectrical contactor 26 by a ring 42. It will be seen that in thepredetermined or aligned position, each interconnection spring element18 has been deformed against a spring force thereof to make electricalcontact with a corresponding electrical terminal 30 of electricalcontactor 26. The predetermined z position is reached by moving the ring42 and the interposer 10 seated therein until the stops 22 bear againstthe side 28 of the electrical contactor 26. In other embodiments, thepredetermined position is reached when sufficient pressure is exerted bythe interconnection spring elements 18 (or the pogo pins or compliantconductive bumps in other embodiments) to keep the contactor 26 inplace. The stops 22 are thus optional. A spacing between the interposer10 and the electrical contactor 26 is such that each of theinterconnection spring elements 18 is under compression.

The ring 42 is formed with a recessed surface 44 which defines a seatfor the interposer 10. The ring 42 has a flat flange-like face 46 whichbears against side 28 of electrical contactor 26. The ring 42 is securedto the electrical contactor 26 by means of fasteners 43, for examplescrews, extending through screw holes 48 (see FIG. 4). The holes 48 aredimensioned to accommodate the fasteners 43 with some degree of play topermit alignment of fiducial markings on the interposer 10 and contactor26, respectively.

FIG. 3 of the drawings shows a first stage in the formation of thecontactor assembly 40. Referring to FIG. 3, a vacuum plate 50 isreleasably secured to a side of the ring 42 opposing face 46 to form asub-assembly 51. The vacuum plate 50 can be connected to a pump (notshown) by means of a coupling 54 and a hose 52 connected to the coupling54. In use, the pump creates a vacuum in a region 56 between the vacuumplate 50 the interposer 10. The vacuum retains interposer 10 against therecessed surface 44. As can be seen from FIGS. 4 and 5, the vacuum plate50 is shaped and dimensioned to provide access to the fasteners 43.

As can be seen from FIG. 6 which shows a sectional view throughsub-assembly 51 taken at 6-6 in FIG. 5, the interposer 10 seats snuglyin the ring 42.

FIG. 7 of the drawings shows a block diagram of how alignment of theinterposer 10 with the electrical contactor 26 is achieved. Theinterposer 10 is seated in the ring 42 and moved in an x, y, or E)direction such that a fiducial marking 58 on the side 14 of theinterposer 10 is aligned with a fiducial marking 60 on the side 28 ofthe electrical contactor 26. Once the fiducial marking 58 is alignedwith the fiducial marking 60, the ring 42 together with the interposer10 is displaced in a z direction so that the ring 42 makes contact withthe electrical contactor 26. A screw 43 located in hole 48 is thenscrew-threaded into a complementary threaded socket 68 formed inelectrical contactor 26. The fiducial markings 58, 60 allow foralignment for the electrical terminals 30 on the electrical contactor 26with the ends of the interconnection spring elements 18 without havingto take an image of the interconnection spring elements 18. Tolerancesin the position of each interconnection spring element in the x-y planeor the angle at which it projects from the x-y plane do not effect thealignment process. The mechanical stops 22 on the side 18 of theinterposer 10 may be used to limit movement of the interposer 10 towardsthe electrical contactor 26 when forming the assembly 40, such that eachof the interconnection spring elements 18 is under the desiredcompression.

FIG. 8 of the drawings shows a perspective view of an alignment machine70, in accordance with one embodiment of the invention, which may beused to align the ring 42 and interposer 10 combination with theelectrical contactor 26. The alignment machine 70 includes a base 72which is shaped and dimensioned to rest on a probe plate 152 which, inuse, houses the electrical contactor 26. The alignment machine 70 alsoincludes a raised platform or plate 74 which is secured to the base 72by means of mounting brackets 76. The platform 74 supports a carriage78. The carriage 78 is seen in FIG. 9 of the drawings which shows a sideview of the alignment machine 70. The carriage 78 is secured to anunderside of the platform 74 by means of a mounting arrangementcomprising angle brackets 88 and horizontal springs 90. The anglebrackets 88 are secured to the platform 74 and provide an anchor for oneend of the springs 90, the other end of the springs 90 being secured toa floating plate 80 of carriage 78 as can be seen in FIG. 9 of thedrawings.

The carriage 78 further includes ring holders 82 which are secured tothe floating plate 80 of vertical members 84 extending between the ringholders 82 and the floating plate 80.

Roller bearings 94 disposed between the platform 74 and the floatingplate 80 allow for slideable displacement of the floating plate 80relative to the platform 74. Vertical springs 95 urge the floating plate80 into contact with roller bearings 94. It will be appreciated that thespring mounting arrangement of the floating plate 80 to the platform 74allows for movement of the floating plate 80 in an x-y plane. Suchmovement in the x y plane is controlled by means of an adjustmentmechanism which, in one embodiment, includes micrometers 96, 98, and100, each of which can be operated to urge a tip thereof to bear againstan edge of the floating plate 80 thereby to cause the displacement offloating plate 80. For example, as can be seen in FIG. 9 of thedrawings, a tip 98.1 of the micrometer 98 may be displaced in a ydirection to bear against an edge of the floating plate 80 thereby tocause the floating plate 80 to be displaced in the y direction. Becausethe ring holders 82 are rigidly connected to the floating plate 80,displacement of the floating plate 80 also causes correspondingdisplacement of the ring holders 82.

In use, the interposer 10 which is seated in the ring 42 by means of asuction force created with the aid of the vacuum plate 50 and a pump(not shown) is connected mechanically to the ring holders 82 of thecarriage 78. Thereafter, the alignment machine 70 is positioned on aprobe plate 152 as is shown in FIG. 10. In this position, the ring 42and the interposer 10 which is seated in the ring 42 is positioneddirectly over the electrical connector 26 which is seated in the probeplate 152.

A magnification system comprising a microscope 102 which includes ascope section 104 and a base 106 is secured on the platform 74 as can beseen in FIG. 9 of the drawings.

The microscope 102 magnifies the fiducial markings 58, 60 on theinterposer 10 and the electrical connector 26, respectively. Themicrometers 96, 98 and 100 may then be operated to move the carriage 78,which carries the ring 42 and the interposer 10 with it, so that theinterposer 10 may be positioned over the electrical connector 26 in apredetermined or aligned position in which the fiducial markings, 58, 60on the interposer 10 and the electrical contactor 26, respectively, arein alignment.

The alignment machine 70, further includes micrometer heads 108 whichmay be operated to move the carriage 78 in a z direction which causesthe interposer and ring combination to be displaced in the z directiontowards the electrical contactor 26. In use, displacement in the zdirection is continued until the stops 22 contact the side 28 ofelectrical contactor 26, or the desired z position is reached. When thisposition is reached, the screws 43 are screwed into the sockets 68 inthe electrical contactor 26, thereby to secure the ring 42 and theinterposer 10 seated therein to the electrical contactor 26.

Once the ring 42 and the interposer 10 are secured to the electricalcontactor 26, the vacuum plate 50 and the alignment machine 70 areremoved. The probe plate 152 may then be aligned to a wafer 32.Thereafter, the probe pate 152 may be secured to a chuck plate 154 whichcarries the wafer 32 (see FIG. 12 of the drawings).

FIG. 12 of the drawings illustrates the components of test probeassembly 160 in accordance with one embodiment of the invention. Thetest probe assembly 150 includes a probe plate 152 and a chuck plate 154which together define a space therebetween for receiving a contactorassembly such as the contactor assembly 40 shown in FIG. 2 of thedrawings.

The chuck plate 154 has a pedestal 156 which provides support for thewafer 32. The probe plate 152 includes a piston 158 which isdisplaceable in a cylinder 160 by a pneumatic (air) means which, in use,is introduced into the chamber 160 through a hose 162 which isreleasably connectable to the cylinder 160. The piston 158 is urgedagainst an electrical contactor 26 of the contactor assembly 40.

In use, air is introduced intro the chamber 160 through hose 162 to urgethe piston 158 to move in a z direction, thereby to displace thecontactor assembly 40 towards the chuck plate 154 until the mechanicalalignment stops 22 on the side 14 of the interposer 10 make contact withthe side 34 of the wafer 32. A resiliently deformable member in the formof an O-ring 163 positioned between the ring 42 and the chuck plate 154serves to limit or control how much displacement of the contactorassembly 40 is produced by movement of the piston 158. Thus, movement ofthe piston 158 does not require precise control. Further, the O-ring 163provides a seal between the ring 42 and the chuck plate 154. The O-ring163 also allows for variations in which the faces 46 of the ring 42 maynot be on the same z-plane by cushioning the ring 42 as it is displacedtowards the chuck plate 154. In some embodiments, the O-ring 163 may bereplaced by springs which provide a reaction against movement of thepiston 158. Once the mechanical stops 22 of the side 14 of theinterposer 10 contact the side 34 of the wafer 32, the interconnectionspring elements are compressed thereby to achieve good electricalcontact between the interconnection spring elements 20 of the interposer10 and the electrical terminals 36 of the wafer 32. Thereafter, the hose162 may be removed. The probe assembly 152 may also include a securingmechanism to releasably secure or fasten the chuck plate 154 to theprobe plate 152. The securing mechanism has not been shown in FIG. 12,but includes any suitable clamping arrangement such as the kinematiccouplings of U.S. Pat. No. 6,340,895 which is hereby incorporated byreference. The test probe assembly 150 may then be inserted into a testburn-in chamber wherein electrical connection pins 166 of an externalinterface component 164 are received in complementary electricalsockets.

Alternatively, the chuck plate 152 may be an integral part of a testprobe unit, and the burn-in testing may be done with the test probeassembly in position above the chuck plate 152 on the test probe unit.

Although the present invention has been described with reference tospecific exemplary embodiments, it will be evident that the variousmodification and changes can be made to these embodiments withoutdeparting from the broader spirit of the invention as set forth in theclaims. Accordingly, the specification and drawings are to be regardedin an illustrative sense rather than in a restrictive sense.

1-19. Cancelled
 20. A method of assembling a test contactor, the methodcomprising: aligning an interposer and an electrical contactor whereinresilient interconnection elements of the interposer are resilientlydeformed to make electrical contact with corresponding electricalterminals on the electrical contactor; and securing the alignedinterposer and electrical contactor together.
 21. The method of claim20, wherein aligning the interposer comprises first aligning theinterposer in an x-y plane over the electrical contactor in a firstposition in which each resilient interconnection element of theinterposer is aligned with its corresponding electrical terminal on theelectrical contactor; and then displacing the interposer in a zdirection to a second position in which each resilient interconnectionelement of the interposer makes contact with a corresponding electricalterminal on the electrical contactor.
 22. The method of claim 21,wherein aligning the interposer further comprises displacing theinterposer in a z direction to a third position wherein each resilientinterconnection element of the interposer is under compression.
 23. Themethod of claim 22, wherein the interposer is in the third position whenstops on the interposer make contact with the electrical connector. 24.The method of claim 21, wherein aligning the interposer in the x-y planecomprises displacing the interposer in an x, y, or a θdirection.
 25. Themethod of claim 21, wherein aligning the interposer in the x-y planecomprises aligning fiducial markings on the interposer and electricalcontactor respectively.
 26. A method of assembling a test contactor fortesting integrated circuits, the method comprising: seating aninterposer in a mount therefore; coupling the mount to an alignmentmachine; adjusting settings on the alignment machine to displace themount relative to an electrical contactor to an aligned position whereinresilient interconnection elements of the interposer are resilientlydeformed to make electrical contact with a corresponding electricalterminal on the electrical contactor; and securing the mount to theelectrical contactor in the aligned position.
 27. The method of claim26, wherein seating the interposer in the mount comprises retaining theinterposer in a seat in the mount using a suction force.
 28. The methodof claim 26, wherein the mount comprises a ring having an annular recesswhich defines the seat.
 29. The method of claim 26, wherein adjustingthe settings comprises adjusting a displacement mechanism of thealignment machine to move the mount in an x-y plane to align fiducialmarkings on the interposer and the electrical contactor respectively.30. The method of claim 29, wherein adjusting the settings furthercomprises adjusting the displacement mechanism to move the mount in a zdirection to bring the interposer in the aligned position.
 31. Themethod of claim 30, wherein displacement in the z direction is limitedby stops between the interposer and the electrical contactor which bearagainst the electrical contactor when the interposer and the electricalcontactor are in the aligned position.
 32. The method of claim 28,further comprising mounting a vacuum plate to one face of the ring andcreating a negative pressure zone between the interposer and the seat.33. The method of claim 32, further comprising removing the vacuum plateafter securing the ring to the electrical contactor.
 34. A method ofassembling a test contactor, the method comprising: aligning aninterposer and an electrical contactor wherein first resilientinterconnection elements of the interposer are resiliently deformed tomake electrical contact with corresponding electrical terminals on theelectrical contactor; securing the aligned interposer and electricalcontactor together to form a sub-assembly; moving the sub-assemblytowards a test substrate to bring second resilient interconnectionelements on the interposer into electrical contact with the testsubstrate; and connecting the electrical contactor to a test probecircuit.
 35. A method of assembling a test contactor, the methodcomprising: positioning an interposer in an x-y plane over an electricalcontactor in a first position in which fiducial markings on theinterposer and the contactor, respectively, are aligned; displacing theinterposer in a z direction to a second position in which a respectiveone of a plurality of resilient interconnection elements of theinterposer makes electrical contact with a respective one of a pluralityof electrical terminals on the electrical contactor; and displacing theinterposer in a z direction to a third position wherein each resilientinterconnection element of the interposer is under compression.